code: def test_iat(self):
      pdf = self.pdf
      psdf = self.psdf
      # Create the equivalent of pdf.loc[3] as a Koalas Series
      # This is necessary because .loc[n] does not currently work with Koalas DataFrames (#383)
      test_series = ps.Series([3, 6], index=["a", "b"], name="3")
  
      # Assert invalided signatures raise TypeError
      with self.assertRaises(
          TypeError,
          msg="Use DataFrame.at like .iat[row_interget_position, column_integer_position]",
      ):
          psdf.iat[3]
      with self.assertRaises(
          ValueError,
          msg="iAt based indexing on multi-index can only have tuple values",
      ):
          psdf.iat[
              3, "b"
          ]  # 'ab' is of length 2 but str type instead of tuple
      with self.assertRaises(
          TypeError,
          msg="Use Series.iat like .iat[row_integer_position]",
      ):
          test_series.iat[3, "b"]
  
      # Assert .iat for DataFrames
      self.assertEqual(psdf.iat[7, 0], 8)
      self.assertEqual(psdf.iat[7, 0], pdf.iat[7, 0])
  
      # Assert .iat for Series
      self.assertEqual(test_series.iat[1], 6)
      self.assertEqual(test_series.iat[1], pdf.loc[3].iat[1])
  
      # Assert invalid column or integer position result in a KeyError like with pandas
      with self.assertRaises(KeyError, msg=99):
          psdf.iat[0, 99]
      with self.assertRaises(KeyError, msg=99):
          psdf.iat[99, 0]
  
      with self.assertRaises(ValueError):
          psdf.iat[(1, 1), 1]
      with self.assertRaises(ValueError):
          psdf.iat[1, (1, 1)]
  
      # Assert setting values fails
      with self.assertRaises(TypeError):
          psdf.iat[4, 1] = 10
  
imports: import datetime
  import unittest
  import numpy
  import pandas
  from pyspark import pandas
  from pyspark.pandas.exceptions import SparkPandasNotImplementedError
  from pyspark.testing.pandasutils import PandasOnSparkTestCase, compare_both
  from pyspark.testing.sqlutils import SQLTestUtils
label_desc: Use image node_id 8 for calling the IndexingAdvMixin obj's underlying member method code with example usage: obj.test_iat() without return types